Present guide catheters generally are formed as a three layer composite tube. A liner is utilized to provide a lubricious surface to aid in device passage through the lumen of the guide. The next layer is a braid material, typically a stainless steel round wire braid, which is positioned directly over the liner. An outer jacket encapsulates the braid and is bonded to the liner through braid interstices to create a monolithic structure from the three components. Typically a liner made in this manner is about 0.002 in. thick, the braid is 0.002 in. thick (0.004 at the crossovers) and the outer jacket thickness is dictated by the outside diameter of the catheter. Typical overall guide catheter wall thicknesses are about 0.010 in., providing a 0.086 in. diameter lumen on an about 0.106 in. catheter. Thinner guide catheter walls are desirable to provide maximum lumen diameter for passage of therapeutic devices.
Guide catheters are typically used in procedures such as percutaneous transluminal coronary angioplasty (PTCA) which are intended to reduce arterial build-up of cholesterol fats or atherosclerotic plaque. Typically a guidewire is steered through the vascular system to the site of therapy. A guiding catheter can then be advanced over the guidewire and finally a balloon catheter advanced within the guiding catheter over the guidewire. A thin wall on the guide catheter will permit passage of a balloon having greater diameter, as is often necessary or desirable.
A number of different catheters have been developed that use braided or coiled reinforcing strands embedded in a plastic wall. Typical of these are the catheter structures described by Truckai in U.S. Pat. No. 5,176,660, Samson in U.S. Pat. No. 4,516,972 and Jaraczewski in U.S. Pat. No. 4,817,613. While providing acceptable torque and column strength, these arrangements tend to show low kink resistance and have undesirably thick walls.
Thus, there is a continuing need for improvements in guide catheters having reduced wall thicknesses with resulting increased lumen diameters while providing improved stiffness and torque transfer characteristics and high kink resistance.